Method and device for assay

A device for assay, the device comprising:na complex part including a first device part and a second device part, wherein the first device part includes a first insoluble carrier housed therein, the first insoluble carrier having a detection portion containing a substance that specifically binds to an analyte, and wherein the second device part has a hole for injecting solution into the first device part, and wherein a second insoluble carrier for developing the solution and a third insoluble carrier for absorbing the solution are housed in the complex part, and wherein the second insoluble carrier and the third insoluble carrier are kept in such a manner that the second insoluble carrier and the third insoluble carrier are partially superimposed and fixed at the detection portion of the first insoluble carrier, and wherein the first insoluble carrier, the second insoluble carrier and the third insoluble carrier are housed in such a manner that they are not in contact with each other, and wherein a pressing unit having a pressing surface that faces the detection portion of the first insoluble carrier is provided in the second device part that faces the detection portion of the first insoluble carrier, and wherein the pressing surface is displaced by being pressed toward the detection portion, and presses, from the upper side of the first insoluble carrier, the second insoluble carrier and the third insoluble carrier onto the first insoluble carrier,wherein when the pressing unit has been pressed toward the detection portion, a clearance between the detection portion and the pressing surface is in the range of 0.01 to 1 mm;wherein a rib that regulates the displacement of the pressing surface by abutting a part of the pressing unit is provided on an inner surface of the first device part, the inner surface facing the pressing unit;wherein a liquid storing pot capable of sending liquids to the gap between the detection portion and the pressing surface is provided in each of the first device part and the second device part, the liquid storing pots being sealed with laminated films; andwherein a reagent solution is injected into the liquid storing pot provided in the first device part, and an amplifying solution that contains silver ions is injected into the second liquid storing pot.